Details of the interviews emerged at a court hearing where Pickering was granted permission not to travel to Leeds for his trial on account of his "frail" state of health.
The 80-year-old was instead allowed to appear on a video link from a court near to the secure psychiatric accommodation where he was held.
Mr Justice King approved an application by Pickering's legal team four days before the start of the trial, which began on March 12.
Pickering's barrister, Sasha Wass, QC, urged the judge to take the unusual step of allowing him not to appear in the dock at Leeds Crown Court.
She said: "He has a number of medical issues which are not unusual for somebody of his age."
Miss Wass said the killer had suffered a heart attack and deep vein thrombosis.
She said his health conditions included high blood pressure and chronic obstructive pulmonary disease.
The barrister said Pickering suffered from a mental disorder but had been assessed by doctors as being fit to stand trial.
Pickering had been held for many years in secure psychiatric accommodation at Thornford Park Hospital, in Reading, Berkshire.
He had previously been held at Broadmoor Hospital, Berkshire and Ashworth Hospital, Liverpool.
Miss Wass said Pickering would have to be moved to a secure facility in Bury, Greater Manchester, for the duration of his trial if he was ordered to attend.
She said that it would lead to delays if he faced a 43-mile journey across the Pennines each morning.
Miss Wass said the travelling could also lead to further problems as Pickering suffered from motion sickness.
Children used by drugs gangs are factor in rising modern slavery figures, says National Crime AgencyShe said: "With the trial and the journey times it is going to exhaust him."
Making the application she said: "It would assist with the smooth running of the trial."
The application was opposed by prosecutors.
Michelle Colbourne, QC, said: "We submit that there is nothing within the evidence to indicate that this is nothing other than an application for the defendant's convenience.
"He is a manipulative defendant who is asking for his own convenience to stay at Reading."
Miss Colbourne said Pickering had been fit enough to take part in 17 interviews during 2017 in relation to the rape and false imprisonment charges..
She added that Pickering had also taken part in a "series of traumatic interviews" with cold case murder detectives in relation to the Elsie Frost murder.
She said: "He has demonstrated a capacity to not have ill effects over what must have been a very grueling series of interviews talking about a previous murder and this rape and he has managed it."
Miss Colbourne said Pickering should appear in court in the interests of open justice.
She added: "There are issues either way and we submit that the best situation is in front of a jury in the dock."
Pickering appeared via a videolink from Swindon Crown Court during the seven day trial, which ended on March 20.
Pickering wore an overcoat throughout most of the trial and sat holding a walking stick.
He occasionally complained about not be able able to hear some of the proceedings.